With the increasing demand for portable consumer electronics, there is a driving need for high-capacity storage devices. Non-volatile semiconductor memory devices, such as flash memory storage packages or sticks, are becoming widely used to meet the ever-growing demands on digital information storage and exchange. Their portability, versatility and rugged design, along with their high reliability and large capacity, have made such memory devices ideal for use in a wide variety of electronic devices, including for example digital cameras, digital music players, video game consoles, PDAs and cellular telephones.
Flash memory storage sticks are coming into use that are fabricated as system-in-a-package (SiP) or multichip modules (MCM), where a plurality of die are mounted on a substrate. The substrate may in general include a rigid base having a conductive layer etched on one or both sides. Electrical connections are formed between the die and the conductive layers, and the conductive layers provide an electric lead structure for integration of the die into an electronic system. Once electrical connections between the die and substrate are made, the assembly is then typically encased in a molding compound to provide a protective package.
In view of the small form factor requirements, as well as the fact that flash memory devices need to be removable and not permanently attached to a printed circuit board, such cards are often built of a land grid array (LGA) package. In an LGA package, the semiconductor die are electrically connected to exposed contact fingers formed on a lower surface of the package. External electrical connection with other electronic components on a host printed circuit board (PCB) is accomplished by bringing the contact fingers into pressure contact with complementary electrical pads on the PCB. LGA packages are ideal for flash memory devices in that they have a smaller profile and lower inductance than pin grid array (PGA) and ball grid array (BGA) packages.
Semiconductor die are typically batch processed on leadframes and then singulated into individual packages upon completion of the fabrication process.
There is a continuing need to increase memory capacity without increasing the dimensions of the flash memory device.
There is also a problem with memory device yield because the individual packages sometimes contain inoperative controller chips, which are the heart of the memory device.
Thus, a need still remains for improving memory devices.
In view of the need, it is increasingly critical that answers be found to these problems. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to reduce costs, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.